What are you guys talking about? The wastegate on the PTK is just after the main crossover pipe between the two headers. How would there be a pressure difference between the two if there is a constant flow? If you had two tanks filled with an equal amount of water and one tank had a shorter line to the drain then the other tank but both were merged, do you think one tank would drain faster? Unless I am totally wrong I would think they would drain at the same rate.

Here is a pic of the wastegate on my PTK kit. My car holds constant boost and does not creep at all. I have the 38mm wastegate and I have a bigger turbo then Ackbar00 and I also have heads and intake.

 

Given the location of the WG in the crossover it is very hard for me to believe that the direction of exhaust flow from the passenger header suddenly reverses direction and exits back through the crossover when the WG is open. Even when the WG is open the exhaust flow from the driver side header is still traveling in the same direction, that is up into the merge collector. Because the WG is open, the driver side just has less pressure than the passenger side. The passenger side header will also see a reduction in pressure as a combined result of pressure loss originating from the drivers side. Remember the pic of Ackbar00's WG being manually opened? The valve looks like it's partially open which is how most WG's are. With the WG in the crossover that WG is only going to bleed off so much pressure before it becomes ineffective. Look at the design of the PTK header, you effectively have the passenger side exhaust flow still exiting into the merge collector uninterupted while the drivers side is dumping exhaust out the WG and still flowing up into the merge collector. Think about the physics involved in it. The flip-side to all this is that some applications have "zero problems" and others have boost gremlins right from the start.:shrug:

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Yep, pretty much what I was thinking.

Now see, this is my brothers TTI Kit. You can see the headers join, then has a wastegate attached.


89coupe - I am banking on that this is my issue. If you ever get a chance to take off you crossover, mabey shine a light down in it and see if you can see any hangover in your pipe. I did not get the pipe welded today, so I cant report if this fixed it yet or not.

 

OK, I had a discussion with a geophysicist at work here and we had a little 101 on Physics and we both came to the conclusion that because the exhaust is travelling at different velocities from one side to the other because of bends and different lengths, the ideal place to have a wastegate on a single turbo setup would be as close to the turbo as possible.

 

OK, the best place to have the wastegate is after the merge, positioned in a manner that the exhaust is "rammed" into the wastegate, for optimum flow. However, it is possible to place the wastegate in the crossover pipe. It will mainly bleed from the bank of cylinders feeding the crossover pipe. However, that is not typically a problem, since the turbo only sees the combined flow. If the turbine housing was a split housing, it might be a problem, but in most instances, provided the wastegate is large enough, it will work fine. Keep in mind that you are reducing the efficiency of the wastegate by positioning it thus, and you will need a bigger wastegate than if you had it optimally positioned.

 

That is correct. But you and I both know why they did what they did..... packaging. There is no room over there!

 

89coupe you are right. that owuld be the BEST place to have it.. however... that is not the only place it would work.

my main question is this... ackbars car ran before and held boost correct ackbar??? so it is not the design of the kit. the design has not changed has it? there really is no mystery here if you ask me... if the kit worked before and it has not changed then the kit should work now... it is something other than the design of the kit... im not saying the kit is ideal... jsut saying what worked before will work now

 

Yes, I agree.

My kit works fine, might not be optimal but it maintains a constant boost pressure.

So yes, I believe Ackbarr00's issue is not design related.

 

The question still remains....has this setup ever worked properly(held consistent boost) at all for you?

 

Yes and No

It seemd to boost correctly on the old motor. I can honestly say that is the last time I got to drive the car, without it braking every weekend. (1.5 Years) That is no bullshit BTW, I have had that many issues. So I really cant give you a informed opnioun. Now, I will say this, before the wastegate almost fell off, the car seemed, to run ok. (now, at this time, I am running a 28 oz motor on 50 oz balancing equipment ) Never really got to drive the car after that. (this was last autum). After that, I replaced the transmission, then I replaced the balancing equipment, then I blew a headgasket, broke the fan and throttle body. As you can see, I have had a hell of a time. It is not untill just recently, that I have been able to REALLY drive the car hard. But I can honeslty say, I really do not remember the car spiking past 15PSI in the gray area inbetween the wastegate almost falling off, till my current problem. I know this really does not help, but thought I would try and lay as much of it out there as I could. I am hoping that this was the problem.

 

I noticed in another thread you said you had a gen 3 kit, is the above pictured header the latest/greatest design?, meaning is there a gen4?

 

That header is a Gen 3. I beleive they have a Gen 4, but I am not sure.

 

I have the Gen 4 kit. My header doesn't appear to reduce to a smaller opening like that. See pics.

 

Ahhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!

No Dice Im dying here. Still got up as high as 15-18 PSI in 4th gear! I tried it with, and with out the boost controller hooked up and the .25 BAR spring. Other thing I thought was well, I have a stock throttle body on because the BBK 75 broke. SO I barow my buddies, Same deal. Sure, it was a bit more responsive, but still saw the high peak!!! It seems like it is not enough wastegate. I know it works great on 89coupe's car, but it is just not working. I have a chance to get another Tial 38 for $70. I am considering buying this and running dual wastegates for no other reason than it is cheaper than getting a $375 44mm one. I mean, I would effectly have a 76mm wastegate, right? If that dont relive enough pressure, I dont know what would.

To make matters worse:
I ran into one of my buddies, He has a 90 GT with GT40 heads and Intake. 36#'rs, Trex, and a Prochager P1SC at 6#. That is it, no hidden NOS, Nothing. We made a few highway rolls. I lost both of them. My car saw a peak of 17#'s. WTF dude? I let him get the jump and I totaly expect to just motor right past him. Did not happen. He would get the jump, and I would hold him there. It looked like I was inching him back in, but nothing that I would have expected. I mean, this car just trapped 121 like 2 weeks ago. Unless my buddy is trapping about the same (With his mods, neither of us think it will), I just dont get it. I swear, I am thinking of taking the car to MD motorsports in Cincy, and saying, "call me when ready!" I mean, this was a MAJOR ego brusier for me. Not to take one thing away form my friends car, but come on. He was as surprised as I was. Just dont get it

 

I'm starting to think you are not seeing 18psi like you think you are. I'd get it on a dyno and run a line straight from your intake to the dyno meter and see what you are truly running.

 

My boost guage and my Profec B both say the same reading. Both come from different points on the intake.

 

not that this has anything to do with the boost problem but have you done a compression check? that may help find out why your buddys 6# sc car beat yours.make sure the car is right mechanically. wish i could help more. yeah i would say go ahead and run that other gate on there... for 70 bucks it cant hurt. i dont know if it would effectively be the same as a 76mm gate but alot better than the one 38 you have... try to get it put in a better spot than the original too that will help. if you want or need any help let me know. i have been in your position before and sometimes some fresh eyes can spot things

 

If you are going by area, dual 38mm would equal 1/2 of a 76mm.

They would also be approx 50% more than a single 44mm.

 

A 38mm wastegate has a 1133 sq. mm valve. Two 38mm wastegates would then have 2266 sq. mm of valve area (about the same as a 54mm wastegate). A 76mm wastegate would have 4534 sq. mm of valve area. Use Pi*r^2 to find area.

A 54mm wastegate is pretty big. Two 38mm wastegates should flow more than enough for your application. For $70, you can't go wrong. Plus, you can put the new wastegate in an optimal location.

 

Why not get it on the dyno instead of continuing to guess? As for the 2nd wastegate idea. I think there may be enough room to mount it righ at the base of the passenger side header by the turbo.